Neither a specific cause(s) nor any specific diagnostic test(s) have been identified for this illness. The range of symptoms, however, suggests there may be subtle perturbations in multiple physiological pathways that are triggered by diverse causes such as infection, stress, brain structure abnormalities, hormone levels, proinflammatory cytokines, etc. Epidemiological evidence is also limited and requires further study. Existing data suggest, however, that CFS occurs three to four times more frequently among women than among men and 10 times more often in white Americans than in Americans of other racial/ethnic groups. A more recent study disputes these numbers and would narrow the gap between the sexes, as well as among racial/ethnic population subgroups.
The cluster of symptoms we know as CFS has been described over the years under many names with varying definitions and suspected causes. But it was not until 1988 that a formal case definition emerged. A brief historical account follows.

In the early 1980s, patients with symptoms including fatigue, muscle pain, and depression were often diagnosed with chronic Epstein-Barr virus syndrome or chronic mononucleosis syndrome. [ 1 ] These patients had symptoms that suggested infection, such as low-grade fever, recurrent sore throat, and tender lymph nodes. Epstein-Barr virus (EBV), which causes acute mononucleosis, was considered a likely source. But researchers could not isolate EBV as the cause of the syndrome and, as yet, have not definitively identified any other infectious agents. Chronic fatigue syndromea formal case definition from the United States

In 1988, in an effort to standardize research definitions, a group of experts led by the Centers for Disease Control and Prevention (CDC) proposed a new name for Epstein-Barr virus syndrome that more accurately described it: chronic fatigue syndrome. [ 2 ] The new definition outlined two major criteria:

Persistent or relapsing, debilitating fatigue, lasting at least 6 months, in a person who has no previous history of similar symptoms; and

Exclusion of other clinical conditions that may produce similar symptoms (e.g., malignancy, autoimmune disease, chronic psychiatric disease, and chronic inflammatory disease, among others).

At the same time as CDC's effort, researchers in Australia developed their own case definition of CFS. [ 3 ] The Australian definition captured CDCs major criteria, and added the symptom of neuropsychiatric dysfunction, which included impairment of concentration and short term memory. CFSthe British definition

A 1990 consensus meeting of researchers in Great Britain found neither of these definitions satisfactory in practice. [ 4 ] The resulting guidelines included a glossary describing in detail the principal symptoms of fatigue, disability, mood disturbance, myalgia (muscle pain), and sleep disturbance. The Oxford criteria, as they came to be known, also defined post-infectious fatigue syndrome (PIFS), a subtype of CFS that either follows an infection or is associated with a current infection. CFSthe International definition

In response to criticisms of the original CDC definition of CFS as too ambiguous and over-exclusive, and to facilitate a more systematic collection of data internationally, the International Chronic Fatigue Syndrome Study Group, headed by CDC and including representatives from Australia and Great Britain, proposed a revised CFS case definition in 1994. [ 5 ] Known as the Fukuda or research definition, it was based on the presence of the following:

Clinically evaluated, unexplained, persistent or relapsing chronic fatigue that is of new or definite onset (has not been lifelong); is not the result of ongoing exertion; is not substantially alleviated by rest; and results in substantial reduction in previous levels of occupational, educational, social, or personal activities.

The concurrent occurrence of four or more of the following symptoms, all of which must have persisted or recurred during 6 or more consecutive months of illness and must not have predated the fatigue:

An expert consensus panel convened in Canada in 2001 and developed a case definition of ME/CFS designed for clinical diagnoses, rather than for research purposes as was the 1994 definition of CFS.[ 6 ] The panel outlined criteria for the symptom categories of fatigue; post-exertional malaise or fatigue; sleep dysfunction; pain; and body system manifestations including neurological/cognitive (e.g., difficulties with memory or concentration), autonomic (e.g., vertigo), neuroendocrine (e.g., heat or cold intolerance), and immune (e.g., sore throat). The international CFS definition revisited

In 2003, the international study group revisited the 1994 case definition of CFS to identify and address ambiguities, with the goal of facilitating future research. [ 7 ] The original definition offered examples of conditions that would preclude a diagnoses of CFS. The study group elaborated on these exclusionary criteria, and recommended the use of several specific standardized instruments in assessing fatigue and accompanying symptoms.

Those links were great. Its very difficult to explain to people what this illness is about. I even have family members who do not think I am sick. At times, especially with casual relationships someone I may run into occasionally but dont know well, people who may have heard through the grapevine I am ill, that I have M.S. because I dont want to see them roll their eyes..........kind of like when I was living in Italy and I would get tired of the reaction, or the long political conversations, when I said I was American, that I was Canadian! lol
Also good point about layman's terms. I am still looking for a simplified but convincing explanation or description also, as I may find myself in a legal situation(not social security related) later this year,where the outcome will completely depend on my having something explaining my poor health. Something that will not be too long and technical that may make the court glaze over fast. Something that would explain the enormous debilitating aspect and the legitimacy of this illness.

Dr. Nancy G. Klimas, who serves on the board of directors of the International Association for Chronic Fatigue Syndrome, is a director of the department of immunology of the University of Miami School of Medicine and director of research for clinical AIDS/H.I.V. research at the Miami Veterans Affairs Medical Center.

But I hope you are not saying that C.F.S. patients are not as ill as H.I.V. patients. My H.I.V. patients for the most part are hale and hearty thanks to three decades of intense and excellent research and billions of dollars invested. Many of my C.F.S. patients, on the other hand, are terribly ill and unable to work or participate in the care of their families.

I split my clinical time between the two illnesses, and I can tell you if I had to choose between the two illnesses (in 2009) I would rather have H.I.V.

But C.F.S., which impacts a million people in the United States alone, has had a small fraction of the research dollars directed towards it.

George I have had this for about 14 yrs. I dont know if Ican actually say I was ever diagnosed. Most doc's I have seen either have not believed it is real or they dont want to talk about it cause they cant offer much help. So by default you might say and the list of symptoms. I am not sure how an illness becomes legitimate.........by number of deaths?

Islandfinn That is very good and to the point. Now if I can figure out how to print it out I will use it as part of my explanation. Thankyou for posting and if you find others I would enormously appreciate it if you would post them.

Also good point about layman's terms. I am still looking for a simplified but convincing explanation or description also, as I may find myself in a legal situation(not social security related) later this year,where the outcome will completely depend on my having something explaining my poor health. Something that will not be too long and technical that may make the court glaze over fast. Something that would explain the enormous debilitating aspect and the legitimacy of this illness.

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You could try to describe your "poor health" in terms of functionality. I can only walk so far before getting tired. If I do x, then y happens. I spend x amount of hours in bed each day and can only use my brain for x amount of time before it shuts down. My temperature rises to x following any activity. I cannot sleep through the night even with medication. I cannot get my own groceries or cook for myself as I cannot stand for more than 5 minutes at a time. I feel fluish and run a low grade temperature most of the time. When I engage in any activity outside basic self-care I end up in bed for three days. I have only one hour a day that I can concentrate.

I'm just making stuff up, but maybe you get the idea? I'm sure we could all help you fine-tune an explanation for you to use.

You might even find some help looking at the type of questions that Social Security asks. They are less concerned with cause and more about what you actually can do. Can you stand? Can you walk? Can you lift things?

Islandfinn That is very good and to the point. Now if I can figure out how to print it out I will use it as part of my explanation. Thankyou for posting and if you find others I would enormously appreciate it if you would post them.

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Hi juniemarie. Welcome to the forums.

here's lots of good info all over the site. Maybe you could start with the Canadian Consensus Documents, the link I've attached is to the overview which is very easy to read.

Also, my last post had a link (click on the words with the blue print) to the NYTimes. They've had a # of good articles - the Oct 12 I think it was one by Denise OGrady is excellent.

Good points gracepoint. All of these suggestions are helping me to get my thoughts organized and focused. I always seems like a bucket of worms when I sit down to write up something. There is A LOT riding on this as far as my future well being and safty is concerned. Sometimes it terrifies me, as I have been alone with it,so appreciate all the input. Plus I think I want to also write something for those family members and "friends" that dont quite believe me when I tell them I am sick.